ALJ may make common sense judgments about functional capacity based on medical findings as long as he does not overstep the bounds of a lay person's competence and render a medical judgment. Evidence regarding claimant's daily activities and demeanor at the hearing, plus doctor's findings of no consistent neurological deficit and no objective evidence of lumbo-sacral root syndrome, constitute substantial evidence to support the finding that claimant's pain, viewed as a non-exertional impairment, did not significantly impair claimant's ability to perform the full range of sedentary work. Whether or not a consultative report of a non-examining physician constitutes substantial evidence depends upon the circumstances of the case.

At Step 4, the ALJ is entitled to credit the claimant's own description of her past work and her functional limitations, but the ALJ has some burden independently to develop the record. Citing Santiago, 944 F.2d 1 (1st Cir. 1991). Remand. Illegibility of non-trivial parts of medical record, combined with identifiable diagnoses and symptoms indicating more than a mild impairment, alerted ALJ to need for expert guidance regarding the extent of the claimant's RFC to perform her past employment. Case remanded. With a few exceptions, an ALJ, as a lay person, is not qualified to interpret raw data in a medical record. Where claimant sufficiently put her inability to perform her past work in issue, the ALJ must measure the claimant's capabilities, and ordinarily an expert's RFC evaluation is essential unless the extent of functional loss, and its effect on job performance, would be apparent even to a lay person. Ventricular tachycardia, frequent PVCs, sinus tachycardia, arterial hypertension

ALJ is not at liberty to substitute her own opinions of an individual's health for uncontroverted medical evidence. ALJ erred in discrediting IQ scores where such test results are the only evidence on the point before the ALJ. It was error for ALJ to conclude that IQ score of 63 must be invalid because claimant had a work history. An IQ score of 63 and a steady work history are not necessarily incompatible. Claimant's work-related functions only became significantly limited when she developed a physical impairment in addition to her mild mental retardation. Under the mental retardation listings for adults, the lowest I.Q. score is to be used in determining whether an adult claimant meets the listing. If claimant's IQ is between 60 and 69, listing 12.05 requires an additional impairment imposing "additional and significant work-related limitation of function," which means that "its effect on a claimant's ability to perform basic work activities is more than slight or minimal." An impairment that meets the severity standard of the sequential evaluation a fortiori satisfies the significant limitations standard.

ALJ is not qualified to interpret raw medical data in functional terms, but in this case, ALJ warranted in finding that claimant's physical impairments do not impose significant exertional limits without medical assessment of RFC. ALJ's observations at hearing were important Avery considerations in light of paucity of medical evidence. ALJ's observation of disability benefits claimant's demeanor at hearing provided substantial evidence for conclusion that nonexertional impairments did not disable claimant, in light of paucity of medical evidence to suggest objective physical basis for disabling pain and vocational expert testimony that claimant could perform the jobs he identified even if she suffered a constant light pain.